Automatic telephone system



C. L. GOODRUM AUTOMATIC TELEPHONE SYSTEM Filed Sept. 22 1919 l/fve/fiarx Char/as L. Good/um y Patented Jan. 2Q, 1%25.

Wire-n srares PATENT c erics.

CHARLES L. GOODRUM, 0, 5 NEVI YORK, N. Y., ASSIG-NOR, T0 VJESTEBJN. ELECTRIC COM- PANY, INCORPORATED, 013 NEW. YORK, N. Y., A CORPORATION OF NEVT YORK.

AUTOMATIC rnnngnonn sYsTnM.

Application. filed September To all whom it may concern:

Be it known that I, CHARLES L. Goomicn, a citizen of the. United States, residing at New York, in the county or New York, State of New York, haveinvented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a' full, clear, concise, and exact description.

This invention relates to telephone ex change systems and more particularly to such systems in which connections are established wholly or inpart by machine switching'mechanism, and wherein such switching mechanism is located in widely-separated offices.

The object of the invention is to provide an improved means for controlling the operation of the machine switching mechanism in exchange systems of this character.

In such systems the electrical impulses necessary for operating the automatic switches do not traverse the entire circuit between the calling station and the distant office, but travel only a portion of such distance, a so-called repeater being relied upon to relay or repeat such impulses in the balance of the circuit extending to the switches of the distant oflice. This arrangement is particularly desirable where long,'heavilyloaded trunks are used, for example, between two distant cities. Owing to the capacity and inductance of long trunk lines it would be diificult to operate automatic switchesat distant oflices by the calling sub scribers, due to weakening and distortion of the impulses.

This invention contemplates an improved repeating arrangement for systems of this character wherein the stepping relay at the originating office has associated with it means so arranged with respect to the outgoing trunk conductors that each time the stepping relay energizes under control of the sender it effects said means in such a manner as to operate a polarized relay at the distant endof the trunk in one direction, and each time the stepping relay deenergizes, it causes said means to operate the polarized relay in the reverse direction. The polarized relay in so operating transmits impulses corresponding exactly in 22, 1913. Serial No. 325.492.

character to those created in the stepping relay circuit in the originating end.

More specifically the invention contemplates a trunk circuit connecting two distant exchanges said circuit being divided into three sections, nductively connected for the transmission of voice currents by two repeatingcoils, one repeating coil being at each end of the trunk circuit. Associated with the repeating coil at one exchange is a stepping relay whose winding is in series with the primary winding of the repeating coil. Contacts on said stepping relay control a pole, changer which operates to send impulses over the trunk conductors to the distant. oliice to operate a polarized relay in series with the primary winding of the repeating coil thereat. An armature and contact of the polarized relay controls a bridge across the secondary of the repeating coil at the distant otlice or the third section of the trunk.

The invention will be more readily understood when described by reference to the accompanying drawing which illustrates only so much of a telephone system as is necessary for a comprehension ofthe invention. The finder and selector switches have been indicated by fixed terminals which are of a type commonly employed in these s itches.

The calling subscriber at substation A upon removing his receiver would set in motion a line finder whose brushes 1, 2 only are shown, since such switches are well known in the art. The calling subscriber is thus connected to a first selector which is then set by the sender operated by the calling subscriber in the well-known man nor to stop the brushes 3, a of the first selector in operative relation to a row of trunks terminating in the office containing the wanted line. The first selector would then, in the well-known manner, automatically pick out an idle one of these trunks. The operation of the apparatus up to this point is well known and therefore neednot he described. It may be of the type shown in United States Patent No. 1,118,910.

hen the idle trunk is found, the relay 6 thereof is energized by a circuit leading to the substation A as follows: free pole of the battery, left-hand winding of relay 6,

conductor 7 winding 8 of the repeating coil 9, conductor 10, contact 4 of the first selector, brush 11 thereof, conductor 12, brush 2 of the finder, contact 13 thereof, line 0011- ductor 14, primary winding 15 of the induction coil at substation A, contact 16 and switchhook 17, transmitter 18, conductor 19, sender 5, finder contact 20, finder brush 1, conductor 21, first selector brush 22, contact 3, conductor 23, winding 24 of repeating coil 9, conductor 25, right-hand winding of'relay 6 to ground. lhe relay 6 at its inner armature and front contact closes a circuit for a slow relay 26 which opens the circuit of release magnet 50 at the first selector. Relay 27 is not energized at this moment due to the battery on the winding of relay 26 being shunted to ground at the contact and outer armatureof relay 6. Relay 26 at its right-hand armature closes the trunk circuit leading to the distantofiice as follows: ground, resistance 28, inner armature and back contact of relay 27, conductor 29, winding 30 of repeating coil 9, conductor 31, winding 32 of repeating coil 41, conductor 42, winding of polarized relay 33, conductor 34, winding 35 of repeating coil 41, conductor 36, winding 37 of repeating coil 9, conductor 38, front contact and righthand armature of relay 26, conductor 39, back contact and outer armature of relay 2?, resistance 40 to grounded battery. Polarized relay 33 at its armature and contact closes the circuit to a selector or connector switch (for simplicity, a connector is diagrammatically shown) over the fol lowing path: grounded battery, lefthand winding of relay 51, upper trunk conductor, winding 52 of repeating coil 41, conductor 42,contact and armature of'polarized relay 33, conductor 54, winding 55 of repeating coil 41, lowertrunk conductor and right-hand winding of relay 51 to ground.

The subscriber at substation A now oper ates his dial 5, in accordance with the tens digit of the number of the wanted line. Each time the circuit of relay 6, above traced, is interrupted by the sender 5, the relay 6 is deenergized and relay 27 is energized over the following path: grounded battery, resistance 43, inner left-hand armature and front contact of relay 26, conductor 44 and winding of relay 27 to ground. Both armatures of relay 27 are attracted and a current of reversed polarity flows through the winding of polarized relay 33 over the following path: grounded battery, resistance 40, outer armature and front contact of relay 2?, conductor 29, winding 30 of repeating coil. 9, conductor 31, winding 32 of repeating coil 41, conductor 42, winding of polarized relay 33, conductor 34, winding 35 of repeating coil 41, conductor 36, winding 37 of repeating coil 9, conductor 38, front contact and right-hand armature of relay 26, conductor 39, front contact and left-hand armature of relay 27 and resistance 28 to ground. Relay 26 is slow to release and does not deenergize during the sending of impulses. This reversal of polarity operates the armature of polarized relay 33 and opens thebridge controlling the connector or selector switches. Each time, during the sending of impulses, that the circuit of relay'G, above traced, is closed, the armatures of relay (5 will be attracted and relay 2? will be deenergized due to the shunt to ground at relay 6. Relay 27 is preferably designed so as to be slightly slow-to-release in order to maintain thepolarized' relay 33 deenergized a sufriciently long,in terval to permit full stepping of the brushes 56 and 57 of the automatic switch. Upon deenergization of relay 2?, its armatures are released and the polarity of current over the circuit'to the polarized relay is again changed which causes its armature to be attracted resulting in the closing of the bridge to the automatic switches. Due to the pole changing relay 2?, the polarized relay causes the bridge ofthe thirdsection of the trunk circuit to be opened and closed in unison with the openings and closures of the bridge including the calling line. The armature of relay 51 in ibrating operates the primary magnet of the connector, which moves the brushes 56 and'57 to the level containing the wanted line in the wellknown manner. At the end of'this series of interruptions, when the sender maintains the line relay energized, the continued energization of the relay 51 at the connector will cause the changeover. operation to take place at the connector to shift the circuit leading from the contact of the relay 51 from operative relation to the primarymagnet of the connector into operative relation with the secondary magnet thereof. The subscriber at substation A now operates his dial 5-in accordance with the units digit of the number of the wanted a line, whereupon the circuit of .relay,6 is again intermittently interrupted, and correspondingly causes the polarized relay 33 to intermittently interrupt the circuit of re lay 51 at the connector.' lmpulses are transmitted by relay 51 at the connector to the secondary magnet thereat to step the connection brushes 56, 57 to the terminals of the wanted line, whereupon the line is tested and if idle, ringing currentis sent thereover, or r if busy, a busy signal is sent back to the calling subscriber. The apparatus for accomplishing these functions may be similar to that shown in thepatent above mentioned.

When the subscriber at substation'B re.-' 1

edbattery, left-hand winding of relay 60,

brush 56, contact 61, over the subscribers loop, contact 62, brush 5? and right-hand windingot relay GO to ground.

Then the calling subscriber at substation A restores his receiver he interrupts atswitchhook l7 and contact 16 of the substation apparatus, the circuit of relay 6. This relay allows its armatures to :t'all back. The inner armature in falling back causes the deenergization oi the slow relay 26, which completes the circuit of release magnet of the first selector over the following circuit: ground, outer left-hand arn'iature and back contact zit-relay 26, contact ca, brush G3, and winding of relay 50 to grounded battery. The right-hand armature of relay 26 in falling back opens the circuit of polarized relay 33, which releases its armature and causes deenergization of relay 51 at the connector, which at its arn'iature and back contact may close the connector release circuit to restore the connector. The ap paratus now restored and ready to be used in establishing another connection.

What is claimed is:

i. In a telephone exchange system, a trunk circuit, an automatic switch, a polarized relay bridged across said trunk circuit for controlling the operation of said switch, a stepping relay, and a pole changing relay arranged to send an impulse of current of one polarity through said polarized relay on energization of said stepping relay and of another polarity on deenergization of said stepping relay.

2. In a telephone exchange system, atrunk circuit, an impulse sending device, a stepping relay responsive to impulses from said sending device, means associated with said stepping relay for converting one impulse of current into two impulses of opposite polarity, and a polarized relay bridged across said trunk circuit operating in response to said impulses.

3. In a telephone exchange system, a trunk circuit divided into three sections, a pair of repeating coils vtor inductively con necting said three sections for voice currents, an impulse sending device, means for conductively relaying impulses from the first to the intermediate of said sections, a polarized relay bridged across the intermediate of said sections controlling a ln'idge across the third of said sections, operating in response to impulses from said sending device.

4. In a telephone exchange system, a trunk circuit divided into three sections, a pair of repeating coils for connecting said three sections inductively for voice currents, an impulse sending device, means for conductively repeating impulses from the first of said sections to the second of said sections, a polarized relay in the second of said sections having a contact and armature for controlling a bridge to the third of said sections, a circuit for operating said polarized relay including the conductors otsaid second section in series and means tor sending a reversal oi": current through said polarized relay at the end of each impulse.

In a telephone exchange system, a trunk line in three'sections, a pair or" repeating coils t'or uniting said sections inductively for voice currents, an impulse sending de vice. a stepping relay, responsive to impulse-s from said sending device, having its windings in series with the primary oi the repeating coil associated with the first and second sections of said trunk line, a slow acting relay controlled by said stepping relay, a pole changer controlled jointly by said stepping relay and said slow acting relay, a polarized relay in series with the primary winding of the repeating coil associated with the second and third sections of said trunk line, controlled by said pole changer, an armature and contact associated with said polarized relay controlling a bridge across the secondary of the repeating coil associated with the second and third sections of said trunk line, and an automatic switch controlled by said bridge.

6. In a telephone exchange system, a trunk circuit divided into three sections inductively connected by a pair of repeating coils for transmission of voice currents, an impulse sending device, a. stepping relay responsive to impulses from said impulse sending device, connected in series with the primary of the repeating coil, associated with the first section of said trunk circuit, a pole changing relay controlled by said stepping relay arranged to send impulses over the second section of said trunk circuit, a polarized relay bridged across the second, section Oi said trunk circuit responsive to impulses from said pole changing relay, a bridge across the third section of said trunk circuit controlled by said polarized relay and an automatic switch controlled by said bridge.

7. In atelephone exchange system, a trunk circuit divided into three sections inductively connected for voice currents, an impulse sending device, a stepping relay in series with the primary winding of the repeating coil. in the first section, a polarized relay bridged across the primary Winding of the intermediate section of said trunk circuit responsive to impulses from said sending device and means for reversing the polarity of the current through said polarized relay during the interval between impulses in order to prepare it for the next impulse.

8. In a telephone system, a. circuit, a stepping relay therein. a trunk circuit including a pair of conductors, a polarized relay and a current source, means for producing impulses in said first circuit to operate said stepping relay, a pole changer operated by said stepping relay to transfer the connections of the poles of said source with said trunk COIlClUCtOl'S to operate said polarized relay by a circuit including said trunk conductors in series and an automatic switch adapted to be set under control of said polarized relay.

9. Ina telephone exchange system, a toll line circuit, a polarized relay bridged across the incoming end of said circuit responsive to reversals of current therethrough, an automatic switch controlled by said relay, an impulse repeating relay associated with the outgoing end of said toll line circuit, and means cooperating with said repeating relay to adjust the reversal of current flow over said toll line so as to permit full stepping of the brushes of the automatic switch in response to actuations of said repeating relay. s

10. In a telephone exchange system, a toll line circuit, a polarized relay bridged across the incoming end of said toll line circuit, an automatic switch controlled by said relay, a source of current associated with the out-- going end of said toll line circuit, impulse repeating means associated with the outgoing end of said toll line circuit, and a relay cooperating with said impulse repeating means to adjust reversals of current flow over said toll line circuit to operate said polarized relay so as to permit full stepping of the brushes of said switch.

In witness whereof, I hereunto subscribe my name this 17th day of September A. D.,

CHARLES L. GOODRUM. 

